Base Solution of Plasma-Lyte A
The del Nido cardioplegia contains a base solution of Plasma-Lyte A, which has an electrolyte composition similar to the extracellular fluid (Baxter Healthcare Corporation, Deerfield, IL). The concentrations of electrolytes before the addition of cardioplegic additives are 140 mEq/L sodium, 5 mEq/L potassium, 3 mEq/L magnesium, 98 mEq/L chloride, 27 mEq/L acetate, and 23 mEq/L gluconate. The manufacturer lists a pH value of 7.4. The cardioplegia additives to this base solution are listed Table 1. This formulation serves as the crystalloid component, which is mixed with blood in a ratio of four parts crystalloid to one part fully oxygenated patient whole blood (usually obtained from the bypass circuit). It is important to note that there is no calcium in the base solution. The final calcium concentration of this cardioplegia can be described as trace because 20% of the delivered volume contains patient blood. This is an important consideration because trace calcium in cardioplegic solutions has been shown to be preferable as compared with acalcemic or normal levels (15,19–21).